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Smart Lightweight Polymer Composites
Published in Sanjay Mavinkere Rangappa, Jyotishkumar Parameswaranpillai, Suchart Siengchin, Lothar Kroll, Lightweight Polymer Composite Structures, 2020
Nayan Ranjan Singha, Mousumi Deb, Manas Mahapatra, Madhushree Mitra, Pijush Kanti Chattopadhyay
Magnetic hysteresis is caused by the alignment of dipoles of a ferromagnetic material in the presence of external magnetic field, followed by the change in orientation and partial nonalignment of the dipoles, if external magnetic field is switched off. Thus, as a result of magnetic hysteresis, part of the aligned dipoles remains unaltered even after the removal of external magnetic field, whereas the remaining dipoles revert back to the unaligned condition. The material experiences energy loss during the magnetic hysteresis as a result of change in rotation of magnetization and size or number of magnetic domains formed by the similarly oriented atoms in a ferromagnetic material. The extent of magnetic hysteresis loss depends mainly on magnetic properties of material, including Rayleigh constant and permeability of material. The Rayleigh constant describes Barkhausen jumps or Barkhausen effect related to the noise in the magnetic output of a ferromagnet in fluctuating magnetic field, which is caused by rapid changes in the sizes of magnetic domains.
B
Published in Carl W. Hall, Laws and Models, 2018
BARDEEN, COOPER, AND SCHRIEFFER THEORY--SEE BCS BARFURTH LAW The axis of the tissues in a regenerating structure of tissue is begins perpendicular to the cut. Keywords: axis, cut, perpendicular, regenerating, tissue BARFURTH, Dietrich, 1849-1927, German anatomist Sources: Friel, J. P. 1974; Gray, P. 1967; Landau, S. I. 1986. BARIC WIND LAW OR BASIC WIND LAW--SEE BUYS BALLOT; STORMS Sources: Fairbridge, R. W. 1967; Huschke, R. E. 1959. BARKHAUSEN EFFECT OR LAW (1919) The succession of abrupt changes or minute jumps in magnetization occurring when the magnetizing force acting on a piece of iron or other magnetic material is varied due to discontinuities in size or orientation of magnetic domains (Fig. B.1). Keywords: change, iron, magnetization BARKHAUSEN, Heinrich Georg, 1881-1956, German electrical engineer Sources: Considine, D. M. 1976; Isaacs, A. 1996; Parker, S. P. 1987. 1989. BAR THEORY OR LAW (1877) Thick deposits of salt, gypsum, and other evaporated material form in oceans or seas or lakes as a result of a lagoon separated from the ocean by a bar in an arid climate. As water is lost by evaporation, additional water of normal salinity flows in from the ocean. The salinity constantly increases as some water is evaporating, reaching a point where salts are deposited. The theory was advanced by C. Ochsenius in 1877. Keywords: evaporates, evaporation, salinity, salt deposits, water OCHSENIUS, Carl, 1830-1906, German geologist Source: Bates, R. L. and Jackson, J. A. 1984. BARUCH LAW When the temperature of the water in a bath is above or below that of the body skin temperature, the effect is stimulating; when the temperatures are same, the effect is sedative.
Magnetic Properties
Published in David Jiles, Introduction to Magnetism and Magnetic Materials, 2015
The Barkhausen effect is the phenomenon of discontinuous changes in the flux density B within a ferromagnet as the magnetic field H is changed continuously. This was first observed in 1919 [8] when a secondary coil was wound on a piece of iron and connected to an amplifier and loudspeaker. As the H field was increased smoothly, a series of clicks were heard over the loudspeaker, which was due to small voltage pulses induced in the secondary coil. These voltages were caused through the law of electromagnetic induction by small changes in flux density through the coil arising from discontinuous changes in magnetization M and hence in the induction B.
Magnetooptical Analysis of the Subsurface Region in a Bearing Ring Subjected to Rolling Contact Fatigue
Published in Tribology Transactions, 2018
Yuri Kadin, Iacopo Bertelli, Andrei Kirilyuk
Optical observation of etched samples is the most common way to analyze subsurface fatigue alteration of steel in bearings; however, one can assume that other material properties also change as a result of RCF. The investigation of magnetic properties is of particular interest, because this knowledge can be useful for the inspection of fatigue damage in bearings by magnetic detection, which, theoretically speaking, can be applied nondestructively. The Barkhausen effect producing the noise in magnetic output due to redistribution of magnetic domains is a nondestructive inspection method that can be used for the detection of fatigue damage in ferromagnetic materials (for example, bearing steel). An attempt to use the Barkhausen effect for the assessment of damage caused by RCF was made in Mazzù, et al. (9) for railway wheel and rail steel and in Diederichs, et al. (10) for bearing steel.
Nondestructive examination of decarburised layer of steels using eddy current and magnetic Barkhausen noise testing techniques
Published in Nondestructive Testing and Evaluation, 2018
S. Falahat, S. Ghanei, M. Kashefi
There is a strong potential for the application of the MBN as a dependable substitute to the standard destructive methods. Unlike ECT which is a high-frequency technique, the MBN performs at very low-frequencies and responds to the differences in magnetic permeability in the ferromagnetic materials [9]. The abrupt and discontinuous changes in magnetisation, named Barkhausen effect, are resulted from a hurried irreversible moving of magnetic domain walls while they are overcoming the pinning sites such as inclusions, grain boundaries, dislocation pile-ups, etc. [10]. These barriers with different intensity of pinning make a distinction between various microstructures. Evaluation of wet and dry grinded surface of AISI 4340 steels [11], determination of surface hardened depth of steels [12,13], assessment of various degree of spheroidisation and its effect on machining properties of high carbon steel components [14], are some examples of the MBN technique application in the field of surface science.
Nonlinear Eddy Current Technique for Fatigue Detection and Classification in Martensitic Stainless-Steel Samples
Published in Research in Nondestructive Evaluation, 2021
Bharath Basti Shenoy, Zi Li, Lalita Udpa, Satish Udpa, Yiming Deng, Vivek Rathod, Thiago Seuaciuc-Osorio
Existing NDE methods for fatigue detection include optical [7,8], acoustic [9,10], magnetic [11,12], and thermal [9,13] methods, and have been applied in metals as well as composites [14–17]. Some of the popular methods are Magneto-Acoustic Emission (MAE), the 3 MA (Micromagnetic Multiparameter Microstructure and Stress Analysis) [18] and Ultrasonic Techniques (UT) [19]. A considerable amount of research has been carried out regarding material ageing at Fraunhofer Institute – IZFP [19]. The MAE technique is sensitive to the environmental noise and has a low signal-to-noise ratio. Further, MAE signal only responds to domains that are at an angle to the applied stress [20]. Typically, fatigue affects the electrical impedance and further alters the magnetic properties of materials due to changes in microstructure [21,22]. Electrical and magnetic NDT methods are senstive to the corresponding characteristics and play a major role in detecting fatigue at an early stage, i.e., before the macro crack initiates. In this area, Magnetic Barkhausen Noise (MBN) has shown promise in fatigue detection and evaluation in carbon steel [20], ferrite steel [23], and martensitic stainless steel [24]. The Barkhausen effect consists of discontinuous changes in magnetic flux density, known as Barkhausen jumps [25]. These are caused by sudden irreversible motion of magnetic domain walls, when they break away from pinning sites due to changes in the applied external magnetic field [26]. Major criticism of MBN is its poor repeatability and stability [27,28]. Further, the MBN measurement is very sensitive to external noise, either due to environment or experimental setup (equipment, sensor, etc.) [24].